1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer program product.
2. Description of the Related Art
Most digital multifunction peripherals (MFP) that are available in the market today have a preview-image display function (hereinafter, “preview function”). In the preview function, image data are displayed on a liquid crystal display (LCD) of a control panel or a screen of a host personal computer (PC). The preview function allows a user to check an image prior to printing it or transmitting it to some other device via a network.
The preview function usually has a magnification altering function that allows an image to be displayed in its entirety or parts thereof displayed in different magnifications. Specifically, the magnification altering function allows the user to view the entire image shrunk to fit in the LCD of the control panel or the screen of the host PC so that the user can get an idea about the image or its density, as well as to view a magnified image of a portion of the image on the LCD of the control panel or the screen of the host PC so that the user can check the details such as whether a minute text in the image is clear or whether a line in the image is intact.
A preview image creation technology is disclosed in Japanese Patent Application Laid-open No. 2006-203702 by which preview images of image data stored in a hard disk are created using the preview function that includes the magnification altering function. In the preview image creating technology, a maximum-resolution preview image is first created in the highest possible resolution that can be selected by the user, and then a preview image is created in the magnification selected by the user based on the maximum-resolution preview image.
When distributing an image data of a scanned image of an original over the network, the digital MFP takes into consideration the type and the file size of the original for performing a gradation process on the scanned image data before sending the image data over the network. For example, a multivalued image data can be distributed as it is, or as a binary image by subjecting the image to a pseudo halftone process, such as an error diffusion process and a dither process, or as a binary image by only subjecting the image to a binarization process. A gradient of the image and text reproduction of the image data that is subjected to a gradation process and an image data that is not subjected to a gradation process are completely different. Therefore, if an image data is subjected to a gradation process before it is distributed over the network, it is preferable that a gradation expression method is the same for the preview image and the output image data.
However, conventionally, the preview images created are of the image data that are subjected only to a magnification process. Therefore, when the image is output after it is subjected to a gradation process, such as pseudo halftone process or a plain binarization, even if preview images of the magnified image are displayed, the gradient of the image and the text reproduction of the output image are altogether different from what is apparent from the preview images. Thus, the user cannot really get an idea about the actual image from the preview image.